Lysosomal Enzymes in fibroblasts

Transcription

1 ERNDIM Administration Office Manchester Centre for Genomic Medicine 6 th Floor, St Mary's Hospital, Oxford Road, Manchester M13 9WL, United Kingdom. Tel: Fax: admin@erndim.org Lysosomal Enzymes in fibroblasts Scientific Advisor Dr Kees Schoonderwoerd Erasmus MC University Medical Center, P.O. Box CA Rotterdam Netherlands g.schoonderwoerd@erasmusmc.nl Scheme Organiser Dr. C.W. Weykamp Queen Beatrix Hospital MCA Laboratory P.O. Box 9005 NL 7100 GG Winterswijk Netherlands c.w.weykamp@skbwinterswijk.nl Annual Report 2017 Date of issue: 31 st January Scheme Design The scheme has been designed, planned and coordinated by Dr Kees Schoonderwoerd as Scientific Advisor and Dr Cas Weykamp as Scheme Organiser (sub-contractor on behalf of SKML); both appointed by and according to procedures laid down by the ERNDIM Board. 2. Samples All EQA materials are lyophilised samples of human fibroblasts. All samples were obtained following local ethical and consent guidelines. Table 1: Samples for the 2017 scheme Sample Disorder Enzyme defect LF1 Tay Sachs beta- Hexosaminidase A LF2 Pompe Alpha-Glucosidase LF3 Krabbe Galactosylceramidase LF4 Niemann-Pick A/B Sfingomyelinase LF5 MPS IV A Galactosamine-6-sulphate sulphatase LF6 Tay Sachs Beta-Hexosaminidase A 3. Shipment One shipment of 6 samples was sent out on the 14 th February 2017, to the 72 laboratories, from 29 countries, which registered for the scheme. 4. Receipt of results There were three submission deadlines from March to September 2017, two before the summer holiday and one after the summer holiday. Laboratories were asked to submit results for each EQA sample by the relevant submission deadline using the results website Laboratories were asked to report the total protein and the activities for 10 enzymes in absolute units and as a percentage of their own laboratories control, see Table 2 for details. Laboratories could submit results for as many, or as few, of these 10 enzymes as they wished. Laboratories were also asked to select an interpretation of the results from a dropdown list on the results website. version: 31 January 2018 Page 1 of 12

2 Table 2: Analytes to be measured Analyte Parameter 1 Parameter 2 Protein mg/vial beta-hexosaminidase A+B 37 degr; nmol/h/mg 37 degr; % mean control alpha-galactosidase nmol/h/mg % mean control beta-galactosidase nmol/h/mg % mean control alpha-glucosidase nmol/h/mg % mean control beta-glucosidase nmol/h/mg % mean control beta-hexosaminidase A nmol/h/mg % mean control alpha-iduronidase nmol/h/mg % mean control Galactosamine-6-sulphate sulphatase nmol/17h/mg % mean control Galactosylceramidase nmol/17h/mg % mean control Sphingomyelinase nmol/h/mg % mean control 5. Scoring scheme For each enzyme 2 criteria were scored: 1) diagnosis and 2) coefficient of variation (). A maximum of 2 points was awarded for each criterion. For the protein value a maximum of 2 points could be scored. Table 3: Scoring criteria Protein Criteria <35% 2 =35 or 35%<<60% 1 >60% 0 Enzymes Diagnosis Diagnosis correct 2 Diagnosis partially correct 1 Diagnosis incorrect 0 <35% 2 =35 or 35%<<60% 1 >60% 0 The maximum possible score for the scheme was 42 points (10 enzymes plus the protein value). Laboratories that participated fully in the scheme (i.e. submitted enough results for their performance to be assessed) but scored less than 60% of their maximum possible score were considered to be unsatisfactory performers in the scheme. For example, if a laboratory submitted results for 8 analytes (protein & 7 enzymes) their maximum possible score would be 30 points so they would need to score 18 or more points to be a satisfactory performer. If 60% of a laboratory s maximum possible score was not a full integer the number of points for satisfactory performance was rounded down to the next full integer Diagnosis The participants must select an interpretation from the dropdown list on the results website. Diagnosis correct indicates correct interpretation and correct measurement of enzyme activity level. In cases of control enzyme activity, the activity should be >15% of the mean control while in case of a patient enzyme activity, the activity should be <30% of the mean control. Diagnosis partially correct indicates incorrect interpretation and correct enzyme activity level or correct interpretation and incorrect enzyme activity level. Diagnosis incorrect indicates incorrect interpretation and incorrect enzyme activity level. version: 31 January 2018 Page 2 of 12

3 5.2. Coefficient of variation Results submitted for samples LF1 and LF 6 were used to calculate the coefficient of variation () according to the following formula. = Activity LF6-activity LF1/mean With only two samples (LF1 and LF6) it was not possible to calculate the standard deviation. 6. Results Sixty-six laboratories (92% of registered laboratories) submitted sufficient results for their performance to be assessed. Six laboratories (8%) did not submit enough results for their performance to be assessed. Full details of each participants results are given in Appendix 1 but summaries are presented here: Over 70% of all laboratories submitted results for 7 or more enzymes, see Table 4. The proficiency per analyte is given in Table 5. Table 6 shows the percentage of the maximum possible score for the laboratories that submitted results. All 66 laboratories that submitted results scored 60% or more of their maximum possible score and were classed as satisfactory performers. Table 4: Number of enzymes for which laboratories submitted results (excluding non- and partial submitters) Number of Enzymes for which results were submitted Number of laboratories Total number of labs 66 version: 31 January 2018 Page 3 of 12

4 Table 5: Proficiency per analyte Analyte No of returns Diagnosis (% 1 ) (% 1 ) Total Proficiency (% 1 ) Protein 71 n.a β-hexosaminidase A+B α-galactosidase β-galactosidase α-glucosidase β-glucosidase β-hexosaminidase A α-iduronidase Galactosamine-6-sulphate sulphatase Galactocerebrosidase Sphingomyelinase = percentage of maximum possible score (for laboratories that submitted results) Table 6: Percentage of maximum possible scores for laboratories that submitted results (excluding partial submitters) %age of maximum possible score No of submitting labs %age of submitting labs 0% 9% 0 0% 10% 19% 0 0% 20% 29% 0 0% 30% 39% 0 0% 40% 49% 0 0% 50% 59% 1 1.5% 60% 69% 5 7.6% 70% 79% % 80% 89% % 90% 99% % 100% 6 9.1% Totals % version: 31 January 2018 Page 4 of 12

5 Table 7: Number of enzymes for which submitting laboratories had satisfactory performance Lab No No of enzymes for which: results were submitted by lab lab had satisfactory performance (partial submitter) (partial submitter) (partial submitter) Lab No No of enzymes for which: results were submitted by lab lab had satisfactory performance (partial submitter) (partial submitter) (partial submitter) version: 31 January 2018 Page 5 of 12

6 Annual Report 2016 (issued: 31 January 2018) 7. Comments on overall scheme performance Overall all samples were correctly interpreted, only for the enzymes α-iduronidase (Hurler), α- Glucosidase and ß-hexosaminidase the % of maximal possible score was just below 90%. For the sample of the Tay-Sachs patient (LF1 and LF6) the was low because of the patient value. 8. Comparison to previous years In 2017 and 2016 arylsulfatase and iduronate-2-sulphate sulphatase activity measurements were not in the scheme, therefore no comparison can be made. For a lot of enzymes and the protein measurements there was an improvement in the reproducibility. Only for ß-Glucosidase, Sphingomyelinase and ß- Hexosaminidase A there was a decrease in the in 2017, especially for ß-Hexosaminidase, probably because of the rather low activity in the duplicate samples. The measurement of galactocerebrosidase activity remains rather difficult, seen the rather high. Table 8: Comparison between data from 2015, 2016 and %age of labs %age of labs with: with: %age of labs with: Analyte No data <35 >35 No of labs No data <35 >35 No of labs No data <35 Protein/vial 10% 80% 10% 71 5% 84% 11% 74 7% 86% 8% 71 α-galactosidase 11% 66% 23% 62 10% 57% 32% 68 5% 74% 21% 66 β-galactosidase 11% 64% 26% 66 6% 73% 22% 69 6% 76% 18% 67 α-glucosidase 10% 63% 27% 48 10% 46% 44% 52 11% 78% 11% 54 β-glucosidase 14% 67% 19% 63 9% 70% 21% 67 10% 67% 24% 67 β-hexosaminidase A 15% 72% 13% 60 7% 70% 24% 59 0% 62% 38% 58 β-hexosaminidase A+B 12% 60% 28% 60 6% 59% 35% 63 3% 76% 21% 63 α-iduronidase 13% 69% 19% 54 7% 70% 23% 57 2% 79% 19% 57 Galactosamine-6- sulphate sulphatase 15% 59% 27% 41 12% 60% 29% 42 5% 70% 25% 44 Galactocerebrosidase 13% 63% 24% 46 10% 52% 38% 48 0% 68% 32% 44 Sphingomyelinase 16% 71% 14% 44 9% 64% 27% 44 5% 68% 27% 44 >35 No of labs Kees Schoonderwoerd Scientific advisor Cas Weykamp Scheme Organiser version: 31 January 2018 Page 6 of 12

7 Appendix 1 (part 1): Results per laboratory (see page 8 for key) Protein/vial Β-Hexosaminidase A+B α-galactosidase β-galactosidase Lab No Diagnosis Diagnosis Diagnosis R0 0 R0 0 0 R d R R ;D ;D version: 31 January 2018 Page 7 of 12

8 Protein/vial Β-Hexosaminidase A+B α-galactosidase β-galactosidase Lab No Diagnosis Diagnosis Diagnosis R0 0 R0 0 1 R0 0 2 R :d R ;D+d R0 0 R0;D+ 0 1 R Key green cells = correct (<35), correct interpretation and correct enzyme level red cells =Incorrect measurement, (>35) or incorrect interpretation or enzyme level blue cells =not all samples measured d- = enzyme activity patient sample > 30% control Fibroblast d+ = enzyme activity other samples < 20 % control Fibroblasts D- = patient sample not indicated as patient in drop down list D+ = sample falsely indicated as patient sample in drop down list D0 = patient sample not measured R0 = calculation not possible as one or both of LF3 and LF6 (duplicate samples) were not measured nd = not detected (i.e. result not submitted) version: 31 January 2018 Page 8 of 12

9 Appendix 1 (part 2): Results per laboratory (see page 8 for key) α-glucosidase β-glucosidase β-hexosaminidase A α-iduronidase Lab No Diagnosis Diagnosis Diagnosis Diagnosis ;d ;d R ;d :d :D ;D- D R0 0 2 R0;D ;d ;d Ro;D0 0 0 R ;D R0;D :D version: 31 January 2018 Page 9 of 12

10 α-glucosidase β-glucosidase β-hexosaminidase A α-iduronidase Lab No Diagnosis Diagnosis Diagnosis Diagnosis R0;D0 0 1 R ;D ;D ;d ;D-d ;D ;D R0 0 2 R ;D ;D d R0;D- 0 1 R0;D ;D ;d ;D- d version: 31 January 2018 Page 10 of 12

11 Appendix 1 (part 3): Results per laboratory (see page 8 for key) Galactosamine-6-sulphate sulphatase Galactocerebrosidase Sphingomyelinase Lab No Diagnosis Diagnosis Diagnosis ;d ;D ;d-d ;D-d R0;D ;D ;D-d ;D ;D ;D- 2 1 R0;D ;d0 2 1 R ;d+ 1 1 version: 31 January 2018 Page 11 of 12

12 Galactosamine-6-sulphate sulphatase Galactocerebrosidase Sphingomyelinase Lab No Diagnosis Diagnosis Diagnosis 47 R ;D ;D+d ;D-d ;D ;d ;D ;d ;D ;D-d ;D version: 31 January 2018 Page 12 of 12